A pathogen normally associated with horses caused severe sinusitis and temporary loss of vision in the right eye of a young woman, doctors have reported.
The infection in the 16-year-old in South Africa has been described in a case report in the journal BMC Opthalmology.
The girl’s sinus infection was found to have been caused by Streptococcus equi subspecies zooepidemicus.
John Kutsukutsa and his colleagues say rhinosinusitis is common, and complications can involve the eyes and intracranial space. Visual loss is an uncommon but recognized complication of bacterial sinusitis.
In the case at hand, testing isolated the bacterium from the maxillary sinus.
The girl underwent emergency endoscopic sinus surgery and antibiotic treatment, which resulted in complete reversal of her vision loss.
Streptococcus equi subsp. zooepidemicus is usually associated with horses, cattle, swine and guinea pigs. In horses, it is most commonly isolated from the uterus of mares.
In humans, infections are uncommon and usually involve a variety of pus-producing clinical signs. It can cause skin and soft tissue infections, septic arthritis, endocarditis, meningitis, pneumonia, pharyngitis, lymphadenitis and osteomyelitis.
Human cases are generally associated with contact with horses, and consumption of unpasteurized milk products, goat cheese or pork.
The case report team says the true incidence of such infections is not known and probably under-reported because few laboratories routinely determine species.
It is, they say, a highly virulent organism, sharing much in common with Streptococcus pyogenes.
It usually infects humans via the respiratory or gastrointestinal tracts and skin.
In the case at hand, the girl had been referred to the Ear Nose and Throat unit at Inkosi Albert Luthuli Central Hospital in Durban with chronic rhinosinusitis. She was being treated with a steroid spray and nasal douche.
She did not have current or recent nasal obstruction. There was no nasal discharge of pus, nor did she complain of any facial pressure. There was no fever, nausea or vomiting, no history of trauma, nor preceding acute illness.
She was a student in a metropolitan high school, did not smoke or consume alcohol, and denied any contact with animals or the consumption of unpasteurised milk.
She reported visiting her rural home about six weeks beforehand but said she did not drink any raw milk or have any contact with horses.
The most pressing concern was declining vision in her right eye.
Imaging and tests were undertaken, but no obvious direct link between loss of vision and the sinusitis was found.
However, there are several known ways in which bacterial sinus infections can cause loss of vision, so a decision was taken to start her on an intravenous antibiotic and perform emergency endoscopic sinus surgery. Pus was found in the sinuses and washed out.
The authors said that, to the best of their knowledge, this organism has not been described as a cause of rhinosinusitis with associated loss of vision.
They noted that infections involving Streptococcus equi subsp. zooepidermicus in humans have been associated with unusual disease presentations that are usually severe.
“Given the growing number of case reports on this pathogen, laboratories should identify the subspecies level in cases Group C Streptococci to allow further characterisation of this infection.”
The case report team comprised Kutsukutsa, Nthabeleng Rankhethoa, Jaivani Sharvani Pillay, Johannes Frederik De Jager, Zaynah Dangor and Yesholata Mahabeer.
Streptococcus equi subsp. zooepidemicus and ‘Neighbourhood syndrome’ –extra-orbitocranial rhinosinusitis with reversible sudden loss of vision- a case report
John Kutsukutsa, Nthabeleng Rankhethoa, Jaivani Sharvani Pillay, Johannes Frederik De Jager, Zaynah Dangor and Yesholata Mahabeer
BMC Ophthalmology 2019 19:117 https://doi.org/10.1186/s12886-019-1126-x